CI: Allow redundant build requests to cancel running CodeQL jobs

Author: amotl

.github/workflows/codeql.yml

@@ -8,6 +8,14 @@ on:
   schedule:
     - cron: "46 2 * * 5"
 
+  # Allow job to be triggered manually.
+  workflow_dispatch:
+
+# Cancel in-progress jobs when pushing to the same branch.
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   analyze:
     name: Analyze